Optics: Convex Lenses
Using an illuminated object, convex lens and screen to determine focal length.
STATUS
This lab is in development.
When complete, this will be a guided, step-by-step 3D simulation of the real physics practical. For now, you can read exactly what the simulation will cover below.
What you’ll do
The guided simulation will walk you through these steps in order.
- 01Set up the optical bench: illuminated object (lamp and cross-wire) at one end, convex lens in a holder in the middle, white screen at the other end.
- 02Move the screen until a sharp, clear image of the cross-wire is formed on it; record the object distance u (object to lens) and image distance v (lens to screen).
- 03Repeat for at least six different values of u (each larger than the focal length).
- 04For each pair, calculate focal length using the formula: 1/f = 1/v − 1/u (using real-is-positive sign convention).
- 05Calculate the mean focal length from all valid readings.
- 06Plot a 1/v vs 1/u graph; the intercepts on each axis both equal 1/f, providing a graphical determination of focal length.